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That's probably the new property list functions done...

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but too tired to test!
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@ -331,7 +331,7 @@ it is not A.
The main application of conditional expressions is in defining functions recursively. The main application of conditional expressions is in defining functions recursively.
#### Example #### Example - recursive function
`ff[x] = [atom[x] -> x; T -> ff[car[x]]]` `ff[x] = [atom[x] -> x; T -> ff[car[x]]]`
@ -373,7 +373,7 @@ The conditional expression is useful for defining numerical computations, as wel
``` ```
|x| = [x<0 -> -x; T -> x] |x| = [x<0 -> -x; T -> x]
``` ```
The factorial of a nonhnegative integer can be defined by The factorial of a non-negative integer can be defined by
``` ```
n! = [n=0 -> 1; T -> n.[n-l]!] n! = [n=0 -> 1; T -> n.[n-l]!]
``` ```
@ -420,7 +420,7 @@ Using the lambda notation, we can write
`ff =` &lambda;`[x] = [atom[x] -> x; T -> ff[car[x]]]` `ff =` &lambda;`[x] = [atom[x] -> x; T -> ff[car[x]]]`
The equality sign in these identities is actually not part of the LISP meta-languageand is only a crutch until we develop the correct notation. The right side of the last equation cannot serve as an expression for the function `ff` because there is nothing to indicate that the occurrence of `ff` inside it stands for the function that is being defined. The equality sign in these identities is actually not part of the LISP meta-language and is only a crutch until we develop the correct notation. The right side of the last equation cannot serve as an expression for the function `ff` because there is nothing to indicate that the occurrence of `ff` inside it stands for the function that is being defined.
In order to be able to write expressions that bear their own name, we introduce In order to be able to write expressions that bear their own name, we introduce
the label notation. If &epsilon; is an expression, and &alpha; is its name, we write label[&alpha;; &epsilon;]. the label notation. If &epsilon; is an expression, and &alpha; is its name, we write label[&alpha;; &epsilon;].
@ -569,26 +569,32 @@ This can be translated into the following S-expression: ,
((QUOTE T)(QUOTE F))))) ((QUOTE T)(QUOTE F)))))
``` ```
- sub st[^;^; z] #### subst[x; y; z]
This function gives the result of substituting the S-expression x for all occurrences
of the atomic symbol y in the S-expression z. It is defined by
###### s~bst[x;~;z] = [eq~al[~;z] -- x;atom[z] - z;T - cons[subst This function gives the result of substituting the S-expression x for all occurrences of the atomic symbol y in the S-expression z. It is defined by
``` ```
[x; y; car[z]]; subst[x;y; cdr[z]]]] subst[x; y; z] = [equal[y; z] -> x;
atom[z] - z;
T - cons[subst
[x; y; car[z]]; subst[x; y; cdr[z]]]]
``` ```
As an example, we have As an example, we have
SU~S~[(X. A);B;((A. B). c)] = ((A. (X. A)). C) ```lisp
null[x] SUBST[(X . A); B; ((A . B) . c)] = ((A . (X . A)) . C)
This predicate is useful for deciding when a list is exhausted. It is true if and ```
only if its argument is NIL.
#### null[x]
This predicate is useful for deciding when a list is exhausted. It is true if and only if its argument is NIL.
The following functions are useful when S-expressions are regarded as lists. The following functions are useful when S-expressions are regarded as lists.
1. append[x; y] #### 1. append[x; y]
append[x; y] = [n~ll[x]-~; T-cons[car [x]; append[cdr [x]; y I]] ```
append[x; y] = [null[x] -> y; T -> cons[car [x]; append[cdr [x]; y]]]
```
An example is An example is
@ -596,175 +602,193 @@ An example is
append[(A B);(C D E)] = (A B C D E) append[(A B);(C D E)] = (A B C D E)
``` ```
2. member[^;^] #### 2. member[x; y]
This predicate is true if the S-expression x occurs among the elements of the
list y. We have
memberlx; y] = [null[y ]--F;
equal[x; car [y ]I--T;
T-member [x; cdr [y I]]
This function gives the list of pairs of corresponding elements of the lists x and This predicate is true if the S-expression `x` occurs among the elements of the list `y`. We have
y, and appends this to the list a. The resultant list of pairs, which is like a table with ```
member[x; y] = [null[y] -> F;
equal[x; car [y ]] ->T;
T -> member[x; cdr [y ]]]
```
#### 3. pairlis[x; y; a]
<a name="page12">page 12</a>
This function gives the list of pairs of corresponding elements of the lists `x` and
`y`, and appends this to the list `a`. The resultant list of pairs, which is like a table with
two columns, is called an association list. We have two columns, is called an association list. We have
``` ```
pairlis [x; y; a] = [null[x]--a; T-cons[cons[car[x]; car[y]]; pairlis [x; y; a] = [null[x] -> a;
pairlis[cdr[x]; cdr [y]; a]]] T -> cons[cons[car[x]; car[y]];
pairlis[cdr[x]; cdr [y]; a]]]
``` ```
An example is An example is
``` ```
pairlis[(A B C);(U V w);((D. X) (E. Y))] = pairlis[(A B C);(U V W);((D . X) (E . Y))] =
((A. U) (B. V) (C. W)(D. X) (E. Y)) ((A . U) (B . V) (C . W)(D . X) (E . Y))
``` ```
4. assoc[x; a] #### 4. assoc[x; a]
If a is an association list such as the one formed by pairlis in the above example,
then assoc will produce the first pair whose first term is x. Thus it is a table searching If `a` is an association list such as the one formed by `pairlis` in the above example,
then `assoc` will produce the first pair whose first term is `x`. Thus it is a table searching
function. We have function. We have
```
assoc[x; a] = [equal[caar[a]; x] -> car[a]; T -> assoc[x; cdr[a]]]
```
An example is An example is
``` ```
assoc[~;((A. (M N)), (B. (CAR X)), (C. (QUOTE M)), (C. (CDR x)))] assoc[B; ((A . (M N)), (B . (CAR X)), (C . (QUOTE M)), (C . (CDR x)))]
= (B. (CAR x)) = (B . (CAR X))
``` ```
5. sublisla; y] ##### 5. sublis[a; y]
Here a is assumed to be an association list of the form ((ul. vl)... (un. v,)),
where the u1 s are atomic, and y is any S-expression. What sublis does, is to treat Here `a` is assumed to be an association list of the form ((u<sub>1</sub>. v<sub>1</sub>)... (u<sub>n</sub> . v<sub>n</sub>)),
the u1 s as variables when they occur in y, and to substitute the corresponding v1 s where the `u`s are atomic, and `y` is any S-expression. What `sublis` does, is to treat
from the pair list. In order to define sublis, we first define an auxiliary function. the `u`s as variables when they occur in `y`, and to substitute the corresponding `v`s
We have from the pair list. In order to define `sublis`, we first define an auxiliary function. We have
sub2[a; z] = [null[a]+z;eq[caar[a]; z]-cdar[a];~-
sub%[cdr[a]; z]] ```
sub2[a; z] = [null[a] -> z; eq[caar[a]; z] -> cdar[a];
T -> sub2[cdr[a]; z]]
```
and and
sublis[a; y] = [at0rn[~]-sub2[a;~]; T-cons[sublis[a; car[^]];
sublis[a; cdr [Y]]]] ```
sublis[a; y] = [atom[y] -> sub2[a; y];
T -> cons[sublis[a; car[y]]; sublis[a; cdr[y]]]]
```
An example is An example is
```
sublis[((X. SHAKESPEARE) (Y. (THE TEMPEST)));(X WROTE Y)] = sublis[((X. SHAKESPEARE) (Y. (THE TEMPEST)));(X WROTE Y)] =
(SHAKESPEARE WROTE (THE TEMPEST)) (SHAKESPEARE WROTE (THE TEMPEST))
The universal function evalquote that is about to be defined obeys the following
identity. Let f be a function written as an M-expression, and let fn be its translation.
(& is an S-expression. ) Let f be a function of n arguments and let args=(argl...
argn), a list of the n S-expressions being used as arguments. Then
``` ```
The universal function `evalquote` that is about to be defined obeys the following identity. Let `f` be a function written as an M-expression, and let `fn` be its translation. (`fn` is an S-expression. ) Let `f` be a function of n arguments and let args=(arg<sub>1</sub>... arg<sub>n</sub>), a list of the `n` S-expressions being used as arguments. Then
`evalquote[fn; args] = f[arg`<sub>1</sub>`... arg`<sub>n</sub>`]`
<a name="page13">page 13</a>
if either side of the equation is defined at all. if either side of the equation is defined at all.
Example Example
fi ~[[x;~];cons[car[x];y]]
fn: (LAMBDA (X Y) (CONS (CAR X) Y)) | | |
argl: (A B) | --------------- | -------------------------------- |
arg2: (C D) | f | &lambda;[[x; y];cons[car[x]; y]] |
args: ((A B) (C D)) | fn | (LAMBDA (X Y) (CONS (CAR X) Y)) |
evalquote[(LAMBDA (X Y) (CONS (CAR X) Y)); ((A B) (C D))] = | arg<sub>1</sub> | (A B) |
~[[x;y];cons[car[x];y]][(A B);(C Dl]= | arg<sub>2</sub> | (C D) |
(A C D) | args | ((A B) (C D)) |
evalquote is defined by using two main functions, called eval and apply. apply
handles a function and its arguments, while eval handles forms. Each of these func- `evalquote[(LAMBDA (X Y) (CONS (CAR X) Y)); ((A B) (C D))] =`
tions also has another argument that is used as an association list for storing the val- &lambda;`[[x;y];cons[car[x];y]][(A B);(C D)] =`
ues of bound variables and f unction names. `(A C D)`
`evalquote` is defined by using two main functions, called `eval` and `apply`. `apply` handles a function and its arguments, while `eval` handles forms. Each of these functions also has another argument that is used as an association list for storing the values of bound variables and function names.
*note here that the environment -- the combination of the object list and the pushdown list -- is said to be an assoc list, where, importantly, it isn't. Of course, for the simplest possible Lisp, it would be -- But (to my surprise) Lisp 1.5 is nothing like the simplest possible Lisp.*
```mexpr
evalquote[fn; x] = apply[fn; x; NIL]
``` ```
```
where where
apply [fn;x; a] = ```mexpr
apply[fn; x; a] =
[atom[fn] -> [eq[fn; CAR] -> caar[x]
eq[fn; CDR] -> cdar[x];
eq[fn; CONS] -> cons[car[x]; cadr[x]];
eq[fn; ATOM] -> atom[car[x]];
eq[fn; EQ] -> eq[car[x]; cadr[x]];
T -> apply[eval[fn; a]; x; a]]
eq[car[fn]; LAMBDA] -> eval[caddr[fn]; pairlis[cadr[fn]; x; a]];
eq[car[fn]; LABEL] -> apply[caddr [fn]; x; cons[cons[cadr [fn];
caddr[fn]]; a]]]
eval[e;a] = [atom[e] -> cdr[assoc[e;a]];
atom[car[e]] -> [eq[car[e]; QUOTE] -> cadr[e];
eq[car[e]; COND] -> evcon[cdr[e]; a];
T -> apply[car[e]; evlis[cdr[el; a]; a]];
T -> apply[car[e]; evlis [cdr[e]; a]; a]]
``` ```
##### [atom[fn] - [eq[fn;~~~] - caar[x] `pairlis` and `assoc` have been previously defined.
``` ```mexpr
eq[fn;~~~] -- cdar[x]; evcon[c; a] = [eval[caar[c]; a] -> eval[cadar[c]; a];
eq[fn; CONS] -- cons[car[x]; cadr[x]]; T -> evcon[cdr [c];a]]
eq[fn;~~~~] -- atom[car[x]];
eq[fn; EQ] - eq[car[x]; cadr[x]];
``` ```
###### T - apply[eval[fn;a];x;a]]
eq[car[fn]; LAMBDA] -- eval[caddr [fn]; pairlis[cadr[fn];x;a]];
###### eq[car [fn]; LABEL] - apply [caddr [fn]; x; cons [cons[cadr [fn]
```
c addr [f n]]; a]]]
eval[e;a] = [atom[e] - cdr[assoc[e;a]];
```
###### atom[car[e]] -
```
[eq[car QUOTE] - cadr [el;
eq[car[e]; COND] - evcon[cdr [el; a];
T -- apply[car [el; evlis[cdr [el; a]; a]];
T - apply[car [el; evlis [cdr [el; a]; a]]
```
pairlis and assoc have been previously defined.
```
evcon[c; a] = [eval[caar [c]; a] -- eval[cadar [c]; a];
T -- evcon[cdr [c];a]]
and and
```mexpr
evlis[m; a] = [null[m] -> NIL;
T -> cons [eval[car [m];a];evlis[cdr [m];a]]]
``` ```
###### evlis[m;a] = [null[m] - NIL <a name="page14">page 14</a>
##### T - cons [eval[car [m];a];evlis[cdr [m];a]]]
We shall explain a number of points about these definitions. We shall explain a number of points about these definitions.
The first argument for - apply is a function. If it is an atomic symbol, then there
are two possibilities. One is that it is an elementary function: car, cdr, cons, eq,
or atom. In each case, the appropriate function is applied to the argument(s). If it is
not one of these, then its meaning has to be looked up in the association list.
If it begins with LAMBDA, then the arguments are paired with the bound variables,
and the form is given to -1 to evaluate.
If it begins with LABEL, then the function name and definition are added to the as-
sociation list, and the inside function is evaluated by apply.
The first argument of is a form. If it is atomic, then it must be a variable,
and its value is looked up on the association list.
If =of the form is QUOTE, then it is a constant, and the value is cadr of the form
itself.
If car of the form is CGND, then it is a conditional expression, and evcon evaluates
the propositional terms in order, and choses the form following the first true predicate.
In all other cases, the form must be a function followed by its arguments. The ar-
guments are then evaluated, and the function is given to apply.
The LISP Programming System has many added features that have not been de-
scribed thus far. These will be treated hereafter. At this point, it is worth noting the
following points.
1. In the pure theory of LISP, all functions other than the five basic ones need to The first argument for `apply` is a function. If it is an atomic symbol, then there are two possibilities. One is that it is an elementary function: `car`, `cdr`, `cons`, `eq`, or `atom`. In each case, the appropriate function is applied to the argument(s). If it is not one of these, then its meaning has to be looked up in the association list.
be defined each time they are to be used. This is unworkable in a practical sense.
The LISP programming system has a larger stock of built-in functions known to the in- If it begins with `LAMBDA`, then the arguments are paired with the bound variables, and the form is given to `eval` to evaluate.
terpreter, and provision for adding as many more as the programmer cares to define.
2. The basic functions car. and cdr were said to be undefined for atomic arguments. If it begins with `LABEL`, then the function name and definition are added to the as-
In the system, they always have a value, although it may not always be meaningful. sociation list, and the inside function is evaluated by apply.
Similarly, the basic predicate eq - always has a value. The effects of these functions
The first argument of `eval` is a form. If it is atomic, then it must be a variable, and its value is looked up on the association list.
If `car` of the form is `QUOTE`, then it is a constant, and the value is `cadr` of the form
itself.
If `car` of the form is `COND`, then it is a conditional expression, and `evcon` evaluates
the propositional terms in order, and choses the form following the first true predicate.
In all other cases, the form must be a function followed by its arguments. The arguments are then evaluated, and the function is given to apply.
The LISP Programming System has many added features that have not been described thus far. These will be treated hereafter. At this point, it is worth noting the following points.
1. In the pure theory of LISP, all functions other than the five basic ones need to be defined each time they are to be used. This is unworkable in a practical sense. The LISP programming system has a larger stock of built-in functions known to the interpreter, and provision for adding as many more as the programmer cares to define.
2. The basic functions `car` and `cdr` were said to be undefined for atomic arguments. In the system, they always have a value, although it may not always be meaningful.
Similarly, the basic predicate `eq` always has a value. The effects of these functions
in unusual cases will be understood after reading the chapter on list structures in the in unusual cases will be understood after reading the chapter on list structures in the
computer. computer.
3. Except for very unusual cases, one never writes (QUOTE T) or (QUOTE F), 3. Except for very unusual cases, one never writes `(QUOTE T)` or `(QUOTE F)`,
but T, and F respectively. but T, and F respectively.
4. There is provision in LISP for computing with fixed and floating point numbers. 4. There is provision in LISP for computing with fixed and floating point numbers. These are introduced as psuedo-atomic symbols.
These are introduced as psuedo-atomic symbols.
The reader is warned that the definitions of apply and ~l given above are pedagogi-
cal devices and are not the same functions as those built into the LISP programming
system. Appendix B contains the computer implemented version of these functions and
should be used to decide questions about how things really work.
11. THE LISP INTERPRETER SYSTEM The reader is warned that the definitions of `apply` and `eval` given above are pedagogical devices and are not the same functions as those built into the LISP programming system. Appendix B contains the computer implemented version of these functions and should be used to decide questions about how things really work.
The following example is a LISP program that defines three functions union, inter- <a name="page15">page 15</a>
section, and member, and then applies these functions to some test cases. The functions
union and intersection are to be applied to "sets," each set being represented by a list ## II. THE LISP INTERPRETER SYSTEM
of atomic symbols. The functions are defined as follows. Note that they are all recur-
sive, and both union and intersection make use of member. The following example is a LISP program that defines three functions `union`, `intersection`, and `member`, and then applies these functions to some test cases. The functions `union` and `intersection` are to be applied to "sets," each set being represented by a list of atomic symbols. The functions are defined as follows. Note that they are all recursive, and both union and intersection make use of member.
``` ```
member[a;x] = [null[x]-~;e~[a;car[x]]-T;T- member[a; x] = [null[x] -> F; eq[a; car[x]] -> T;
member [a;cdr [x]]] T -> member[a; cdr[x]]]
union[^;^] = [null[x]-.y;member[car[x];y]-union
[cdr [x];~]; T-cons [c ar [x];union[c dr [x];~]]] union[x; y] = [null[x] -> y;
member[car[x];y] -> union[cdr[x]; y];
T -> cons[car[x]; union[cdr[x]; y]]]
intersection[x;y] = [null[x] -> NIL;
member[car[x]; y] -> cons[car[x]; intersection[cdr[x]; y]];
T -> intersection[cdr[x]; y]]
``` ```
To define these functions, we use the pseudo-function define. The program looks like To define these functions, we use the pseudo-function define. The program looks like
@ -2680,7 +2704,7 @@ The function `deflist` is a more general defining function. Its first argument i
If `deflist` or `define` is used twice on the same object with the same indicator, the old value will be replaced by the new one. If `deflist` or `define` is used twice on the same object with the same indicator, the old value will be replaced by the new one.
#### attrib[x;e] : SUBR pseudo-function #### attrib[x; e] : SUBR pseudo-function
The function attrib concatenates its two arguments by changing the last element of its first argument to point to the second argument. Thus it is commonly used to tack something onto the end of a property list. The value of attrib is the second argument. The function attrib concatenates its two arguments by changing the last element of its first argument to point to the second argument. Thus it is commonly used to tack something onto the end of a property list. The value of attrib is the second argument.
@ -2712,47 +2736,45 @@ cator is found, and NIL otherwise.
This pseudo-function is used to create a constant by putting the indicator APVAL This pseudo-function is used to create a constant by putting the indicator APVAL
and a value on the property list of an atomic symbol. The first argument should be an and a value on the property list of an atomic symbol. The first argument should be an
atomic symbol; the second argument is the value is cons[val;N1~]. atomic symbol; the second argument is the value is cons[val;N1~].
```
csetq[ob;val] - FEXPR pseudo-function #### csetq[ob; val] : FEXPR pseudo-function
csetq is like cset - except that it quotes its first argument instead of evaluating it.
#### remprop[x; ind] : SUBR pseudo-function
* csetq is like cset - except that it quotes its first argument instead of evaluating it.
rempr op[x; ind] : SUBR pseudo-function f
The pseudo-function remprop searches the list, x, looking for all occurrences of the The pseudo-function remprop searches the list, x, looking for all occurrences of the
indicator ind. When such an indicator is found, its name and the succeeding property indicator ind. When such an indicator is found, its name and the succeeding property
are removed from the list. The two "endsn of the list are tied together as indicated by are removed from the list. The two "endsn of the list are tied together as indicated by
the dashed line below. the dashed line below.
```
The value of remprop is NIL. The value of remprop is NIL.
When an indicator appears on a property list without a property following it, then When an indicator appears on a property list without a property following it, then
it is called a flag. An example of a flag is the indicator TRACE which informs the inter- it is called a flag. An example of a flag is the indicator TRACE which informs the inter-
preter that the function on whose property list it appears is to be traced. There are two preter that the function on whose property list it appears is to be traced. There are two
pseudo-functions for creating and removing flags respectively. pseudo-functions for creating and removing flags respectively.
```
- flag [I; ind] EXPR pseudo-function #### flag [I; ind] : EXPR pseudo-function
```
The pseudo-function flag puts the flag ind on the property list of every atomic symbol The pseudo-function flag puts the flag ind on the property list of every atomic symbol
in the list 1. Note that d cannot be an atomic symbol, and must be a list of atomic sym- in the list 1. Note that d cannot be an atomic symbol, and must be a list of atomic sym-
bols. The flag is always placed immediately following the first word of the property bols. The flag is always placed immediately following the first word of the property
list, and the rest of the property list then follows. The value of flag is NIL. No property list, and the rest of the property list then follows. The value of flag is NIL. No property
list ever receives a duplicated flag. list ever receives a duplicated flag.
remflag[l; ind] : EXPR pseudo-function
#### remflag[l; ind] : EXPR pseudo-function
remflag removes all occurrences of the indicator ind from the property list of each remflag removes all occurrences of the indicator ind from the property list of each
atomic symbol in the list 8. It does this by patching around the indicator with a rplacd atomic symbol in the list 8. It does this by patching around the indicator with a rplacd
in a manner similar to the way remprop works. in a manner similar to the way remprop works.
```
``` ### Table Building and Table Reference Functions
Table Buildinrr and Table Reference Functions
``` #### pair [x; y] : SUBR
The function pair has as value the list of pairs of corresponding elements of the lists x and y. The arguments x and y must be lists of the same number of elements. They should & be atomic symbols. The value is a dotted pair list, i. e. ((a (a p2)...
- pair [x; y] SUBR
The function pair has as value the list of pairs of corresponding elements of the lists
x and y. The arguments x and y must be lists of the same number of elements. They
should & be atomic symbols. The value is a dotted pair list, i. e. ((a (a p2)...
pair[x;y] = [prog[u;v; m] pair[x;y] = [prog[u;v; m]
u:= x; u:= x;
v:= y; v:= y;
@ -2765,7 +2787,10 @@ m:= cons[cons[car[u];car[v]];m];
u:= cdr[u]; u:= cdr[u];
v:= cdr[v]; v:= cdr[v];
go[~Il go[~Il
sassoc[x;y;u] SUBR functional ```
#### sassoc[x; y; u] : SUBR functional
The function sassoc searches y, which is a list of dotted pairs, for a pair whose first The function sassoc searches y, which is a list of dotted pairs, for a pair whose first
element that is x. If such a pair is found, the value of sassoc is this pair. Otherwise element that is x. If such a pair is found, the value of sassoc is this pair. Otherwise
the function u of no arguments is taken as the value of sassoc. the function u of no arguments is taken as the value of sassoc.
@ -2781,12 +2806,12 @@ the S-expression y in the S-expression z.
T .- cons[subst[x;y;car [z]];subst [x;y;cdr[e]]]] T .- cons[subst[x;y;car [z]];subst [x;y;cdr[e]]]]
* sublis [x ; y] SUBR #### sublis [x ; y] : SUBR
Here x is a list of pairs, Here x is a list of pairs,
((ul vl) (u2 v2) (un vn)) ((u<sub>1</sub> . v<sub>1</sub>) (u<sub>2</sub> . v<sub>2</sub>) (u<sub>n</sub> . v<sub>n</sub>))
The value of sublis[x;y] is the result of substituting each v for the corresponding The value of `sublis[x; y]` is the result of substituting each `v` for the corresponding
u in y. `u` in `y`.
Note that the following M-expression is different from that given in Section I, though Note that the following M-expression is different from that given in Section I, though
the result is the same. the result is the same.
@ -2819,38 +2844,33 @@ nconc does not copy its first argument.
* conc concatenates its arguments without copying them. Thus it changes existing list * conc concatenates its arguments without copying them. Thus it changes existing list
structure and is a pseudo-function. The value of conc is the resulting concatenated list. structure and is a pseudo-function. The value of conc is the resulting concatenated list.
nc - onc [x;y] SUBR pseudo-function #### nconc [x; y] : SUBR pseudo-function
``` The function `nconc` concatenates its arguments without copying the first one. The
The function nconc concatenates its arguments without copying the first one. The
operation is identical to that of attrib except that the value is the entire result, (i. e. the operation is identical to that of attrib except that the value is the entire result, (i. e. the
modified first argument, x). modified first argument, x).
The program for nconc[x;y] has the program variable m and is as follows: The program for nconc[x;y] has the program variable m and is as follows:
```
nconc [x; y ] = prog [[m]; nconc [x; y ] = prog [[m];
[null[x] - return[~]]
``` ```
##### [null[x] - ret~rn[~]] #### COPY [X] : SUBR
* COPY [XI SUBR
```
This function makes a copy of the list x. The value of copy is the location of the This function makes a copy of the list x. The value of copy is the location of the
copied list. copied list.
```
##### copy[x] = [null[x] - ~~~;atom[x] - x;T -- cons[copy[car[x]] copy[x] = [null[x] - ~~~;atom[x] - x;T -- cons[copy[car[x]]
``` ```
co~[cdr[xllIl co~[cdr[xllIl
``` ```
``` #### reverse[t] : SUBR
reverseit] SUBR
```
```
This is a function to reverse the top level of a list. Thus This is a function to reverse the top level of a list. Thus
reverse[(^ B (C. D))] = ((C D) B A)) reverse[(A B (C. D))] = ((C D) B A))
reverse[t] = prog[[v]; reverse[t] = prog[[v];
u: =t; u: =t;
``` ```
@ -2915,7 +2935,7 @@ m:= cdr[m];
go[~oopl1 go[~oopl1
#### search[x; p; f; u] : SUBR functional #### search[x; p; f; u] : SUBR functional
The function search looks through a list x for an element that has the property p, and if such an element is found the function f of that element is the value of search. If there is no such element, the function u of one argument x is taken as the value of search (in this case x is, of course, NIL). The function search looks through a list x for an element that has the property p, and if such an element is found the function f of that element is the value of search. If there is no such element, the function u of one argument x is taken as the value of search (in this case x is, of course, NIL).
Arithmetic Functions Arithmetic Functions

9
resources/lisp1.5.lsp
View file

@ -147,4 +147,11 @@
((ATOM Z) Z) ((ATOM Z) Z)
((QUOTE T) (CONS (SUBST X Y (CAR Z)) (SUBST X Y (CDR Z)))))) ((QUOTE T) (CONS (SUBST X Y (CAR Z)) (SUBST X Y (CDR Z))))))
(SYSIN) (SYSIN)
(SYSOUT) (TERPRI) (TIMES) (TRACE) (UNTRACE) (ZEROP LAMBDA (N) (EQ N 0))) (SYSOUT) (TERPRI) (TIMES) (TRACE)
(UNION LAMBDA (X Y)
(COND
((NULL X) Y)
((MEMBER (CAR X) Y) (UNION (CDR X) Y))
(T (CONS (CAR X) (UNION (CDR X) Y)))))
(UNTRACE)
(ZEROP LAMBDA (N) (EQ N 0)))

112
src/beowulf/host.clj
View file

@ -164,17 +164,32 @@
(number? value) (number? value)
(symbol? value) (symbol? value)
(= value NIL)) (= value NIL))
(do (try
(.rplaca cell value) (.rplaca cell value)
cell) cell
(catch Throwable any
(throw (ex-info
(str (.getMessage any) " in RPLACA: `")
{:cause :upstream-error
:phase :host
:function :rplaca
:args (list cell value)
:type :beowulf}
any))))
(throw (ex-info (throw (ex-info
(str "Invalid value in RPLACA: `" value "` (" (type value) ")") (str "Invalid value in RPLACA: `" value "` (" (type value) ")")
{:cause :bad-value {:cause :bad-value
:detail :rplaca}))) :phase :host
:function :rplaca
:args (list cell value)
:type :beowulf})))
(throw (ex-info (throw (ex-info
(str "Invalid cell in RPLACA: `" cell "` (" (type cell) ")") (str "Invalid cell in RPLACA: `" cell "` (" (type cell) ")")
{:cause :bad-value {:cause :bad-cell
:detail :rplaca})))) :phase :host
:function :rplaca
:args (list cell value)
:type :beowulf}))))
(defn RPLACD (defn RPLACD
"Replace the CDR pointer of this `cell` with this `value`. Dangerous, should "Replace the CDR pointer of this `cell` with this `value`. Dangerous, should
@ -189,17 +204,32 @@
(number? value) (number? value)
(symbol? value) (symbol? value)
(= value NIL)) (= value NIL))
(do (try
(.rplacd cell value) (.rplacd cell value)
cell) cell
(catch Throwable any
(throw (ex-info
(str (.getMessage any) " in RPLACD: `")
{:cause :upstream-error
:phase :host
:function :rplacd
:args (list cell value)
:type :beowulf}
any))))
(throw (ex-info (throw (ex-info
(str "Invalid value in RPLACD: `" value "` (" (type value) ")") (str "Invalid value in RPLACD: `" value "` (" (type value) ")")
{:cause :bad-value {:cause :bad-value
:detail :rplaca}))) :phase :host
:function :rplacd
:args (list cell value)
:type :beowulf})))
(throw (ex-info (throw (ex-info
(str "Invalid cell in RPLACD: `" cell "` (" (type cell) ")") (str "Invalid cell in RPLACD: `" cell "` (" (type cell) ")")
{:cause :bad-value {:cause :bad-cell
:detail :rplaca}))));; PLUS :phase :host
:detail :rplacd
:args (list cell value)
:type :beowulf}))));; PLUS
(defn LIST (defn LIST
[& args] [& args]
@ -394,38 +424,54 @@
(make-beowulf-list (map CAR @oblist)) (make-beowulf-list (map CAR @oblist))
NIL)) NIL))
(defn PUT
"Put this `value` as the value of the property indicated by this `indicator`
of this `symbol`. Return `value` on success.
NOTE THAT there is no `PUT` defined in the manual, but it would have been
easy to have defined it so I don't think this fully counts as an extension."
[symbol indicator value]
(let [magic-marker (Integer/parseInt "777778" 8)]
(if-let [binding (ASSOC symbol @oblist)]
(if-let [prop (ASSOC indicator (CDDR binding))]
(RPLACD prop value)
(RPLACD binding
(make-cons-cell
magic-marker
(make-cons-cell
indicator
(make-cons-cell value (CDDR binding))))))
(swap!
oblist
(fn [ob s p v]
(make-cons-cell
(make-beowulf-list (list s magic-marker p v))
ob))
symbol indicator value))))
(defn DEFLIST
"For each pair in this association list `a-list`, set the property with this
`indicator` of the symbol which is the first element of the pair to the
value which is the second element of the pair."
[a-list indicator]
(map
#(PUT (CAR %) indicator (CDR %))
a-list))
(defn DEFINE (defn DEFINE
"Bootstrap-only version of `DEFINE` which, post boostrap, can be overwritten "Bootstrap-only version of `DEFINE` which, post boostrap, can be overwritten
in LISP. in LISP.
The single argument to `DEFINE` should be an assoc list which should be The single argument to `DEFINE` should be an association list of symbols to
nconc'ed onto the front of the oblist. Broadly, lambda functions"
(SETQ OBLIST (NCONC ARG1 OBLIST))" [a-list]
[args] (DEFLIST a-list 'EXPR))
(swap!
oblist
(fn [ob arg1]
(loop [cursor arg1 a arg1]
(if (= (CDR cursor) NIL)
(do
(.rplacd cursor @oblist)
(pretty-print a)
a)
(recur (CDR cursor) a))))
(CAR args)))
(defn SET (defn SET
"Implementation of SET in Clojure. Add to the `oblist` a binding of the "Implementation of SET in Clojure. Add to the `oblist` a binding of the
value of `var` to the value of `val`. NOTE WELL: this is not SETQ!" value of `var` to the value of `val`. NOTE WELL: this is not SETQ!"
[symbol val] [symbol val]
(when (PUT symbol 'APVAL val))
(swap!
oblist
(fn [ob s v] (if-let [binding (ASSOC symbol ob)]
(RPLACD binding v)
(make-cons-cell (make-cons-cell s v) ob)))
symbol val)
val))
;;;; TRACE and friends ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;; TRACE and friends ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

3
src/beowulf/reader/parser.clj
View file

@ -64,7 +64,8 @@
cond := lsqb (opt-space cond-clause semi-colon opt-space)* cond-clause rsqb; cond := lsqb (opt-space cond-clause semi-colon opt-space)* cond-clause rsqb;
cond-clause := mexpr opt-space arrow opt-space mexpr opt-space; cond-clause := mexpr opt-space arrow opt-space mexpr opt-space;
arrow := '->'; arrow := '->';
args := mexpr | (opt-space mexpr semi-colon opt-space)* opt-space mexpr opt-space; args := arg | (opt-space arg semi-colon opt-space)* opt-space arg opt-space;
arg := mexpr | sexpr;
fn-name := mvar; fn-name := mvar;
mvar := #'[a-z][a-z0-9]*'; mvar := #'[a-z][a-z0-9]*';
mconst := #'[A-Z][A-Z0-9]*'; mconst := #'[A-Z][A-Z0-9]*';